<!DOCTYPE html>
<html>
    <script>
        function a(){
            c();        //()调用
            //c.apply(null);//apply调用
            //c.call(null); //call调用
        }
        function c(){alert(arguments.callee.caller);}
        a();
        a.apply(null);
        a.call(null);
    </script>
</html>